Sulfur and metal containing compound



- exam. no,

October 22, 1966 UNITED STATES PATENT @FFICE SULFUR AND METAL CONTAININGCOM'POUND Delaware No Drawing. Application August 1, 1944, Serial No.547,640

2 Claims.

This invention relates to a novel type of organic compound containingsulfur and a metal.

This is a continuation-impart of our co-pending application Serial No.486,428, filed May 10, 1943.

It is known that the addition of certain types of metal organiccompounds to lubricating oils improves various properties thereof, suchas their oiliness characteristics and their detergent action in engines,particularly manifested in the maintenance of a clean engine conditionduring operation. Various metal compounds which have been used for suchpurposes include the metal derivatives of such organic compounds asfatty acids, naphthenic acids, sulfonic acids, alcohols, phenols andketones. However, these various metal compounds generally have thedisadvantage of tending to corrode alloy bearings, such as those ofcadmium-silver and copper-lead, now so widely used in automotiveengines, and this is especially true in engines which operate atrelatively high speeds and high temperatures. It is an object of thepresent invention to provide a new class of addition agents for oilswhich are to be used as crankcase lubricants for internal combustionengines and which exhibit the desirable properties of promoting generalengine cleanliness, improving oil film strength, reducing ring sticking,piston skirt varnish formation and the like, and which not only do notexhibit the corrosion promoting tendencies characteristic of the abovemetal compounds, but also inhibit the corrosiveness of oils to whichthey are added.

The new class of products which have now been found to be highlysatisfactory as addition agents are the products obtained by thereaction of elemental sulfur with metal salts of hydroxy and mercaptosubstituted aromatic sulfides. When these compounds are to be used asadditives for mineral oils, they should contain as a substituent in thearomatic nucleus at least one alkyl group, the total number of carbonatoms in such groups being at least five. It has been found that suchproducts are usually satisfactory in inhibiting bearing corrosion and inbeing adaptable to use with a wide variety of petroleum lubricating oilbase stocks. The reaction for the preparation of the additives maygenerally be brought about in a solution of lubricating oil or otherpetroleum oil, whereby concentrates may be prepared which may beconveniently stored or shipped and added to lubricating oils whenrequired.

The new sulfur containing compositions herein described are also usefulas antioxidants for other purposes when incorporated in organicmaterials products in lubricating oil compositions.

other than lubricating oils, as will be more fully explainedhereinafter, and in some cases it may not be necessary to have alkylgroups present in order to impart sufiicient solubility. The inventionalso includes the reaction products of sulfur with compounds analogousto the salts of phenol sulfides and thiophenol sulfides, but containingselenium and tellurium in place of oxygen or sulfur, and with compoundsin which aromatic nuclei other than benzene nuclei are present.

In the aforementioned co-pending application Serial Number 486,428 wehave described the preparation of reaction products of elemental sulfurwith metal phenates and the use of such It was there shown that thesulfur atoms were probably linked directly to the metal atoms in themolecules of the reaction product. It is believed that the same type ofreaction occurs when metal salts of phenol sulfides and the like aretreated with sulfur, giving compounds in which the sulfur atoms arethought to be attached directly to the metal atom.

Some of the more preferred products to be used in accordance with thepresent invention are those obtained by reaction of sulfur with thefollowing compounds:

Barium tert.-octyl phenol sulfide Barium di-tert.-amyl phenol sulfideCalcium isohexadecyl phenol sulfide Tin wax-alkylated salicylic acidsulfide Magnesium tert.-amyl phenol sulfide The invention includes thereaction products of sulfur with not only the normal metal salts ofphenol sulfides, thiophenol sulfides and the like, but the basic metalsalts as well. In a normal phenol sulfide salt of a divalent metal theratio of metal to phenol sulfide is 1:1 as in the folowing formula:

In a basic salt the ratio of metal to phenol sulfide may be 2:1 or even3:1. In the case of a 2:1 ratio the formula may, for example, be

MOH MOE 3 In the case of a 1.5: 1 ratio the formula may be MOH MOH MO oIn the case of a 3:1 ratio the formula may be MOH M011 Intermediateratios of metal to phenol sulfide, such as 1.8:1 or 2.311, may occur in'which mixtures of the above types of basic compounds are obtained. Thesebasic salts are formed, for example, by reacting phenol sulfides withmore than the amount of metallic oxide or hydroxide necessary to formthe normal salts. Reaction products of sulfur with basic metal salts ofalkyl phenol sulfides are particularly useful in extreme pressurelubricants. These products are also especially advantageous forimparting color stability to lubricants.

The new class of addition agents employed in accordance with the presentinvention may be defined in its broadest scope as the reaction productsof elemental sulfur with a metal salt of a compound having the formulain which Ar is an aromatic nucleus and may, for illustration, be abenzene nucleus, or it may consist of a plurality of rings, as inbiphenyl, or it may be a condensed nucleus, exemplified by naphthalene,anthracene and the like. R in the formula is hydrogen or at least oneorganic group and is preferably an alkyl group. X in the formula is anon-metal of group VI of the periodic table; Y is a member of the sulfurfamily; a: is an integer from 1 to 4; and R, is an organic group whichmay be either aryl, alkyl, aralkyl, or alkylaryl, and which may containsubstituent atoms or groups, such as halogen, nitro, amino, hydroxy,alkoxy, aroxy, mercapto, carboxy, and the like. The metals which may besubstituted for the hydrogen in the -XH group of the above formula informing salts of such compounds may be any metals, the most importantfor the purposes of the present invention being calcium, barium,strontium, magnesium, and zinc, although for some purposes correspondingcompounds containing tin, lead, aluminum, cobalt or nickel will also befound to be especially desirable.

Compounds particularly suited for the purposes of the present inventionare formed by reacting sulfur with a compound of the formula where Rrepresents at least one alkyl radical attached to the nucleus, the totalnumber of carbon atoms in all of such radicals being at least five whenthe compound is to be dissolved in hydrocarbon oils, X is oxygen orsulfur, M is a divalent metal of group 11 of the periodic table, and a:is an integer from 1 to 4.

It should be understood that the above general formulas includecompounds in which various substituent atoms or groups may be attachedto the aromatic nucleus, such as alkyl, cycloalkyl, aralkyl, aryl,carboxyl, hydroxyl, alkoxy, aroxy, sulfhydryl, nitro, ester (organicand/0r inorganic), keto, amino, aldehydo, chlormethyl. aminomethyl,alkyl thiomethyl, alkyl xanthomethyl, metal substituted carboxyl, metalsubstituted sulfonic acid, metal substituted hydroxyl or sulfhydrylgroups, halogen atoms, etc. Different types of atoms or groups may beattached to the same aromatic nucleus. Alkyl radicals attached to thenucleus may have a total of five to twelve carbon atoms in all of suchgroups, but in some cases as many as sixteen to twenty or more carbonatoms in a single group, or a plurality of groups, may be preferred. Ifmore than one alkyl group is present in a single molecule, whether ornot attached to the same aryl nucleus, such groups may be alike ordifferent. Such allzyl or other hydrocarbon groups may containsubstituent groups, such as those named above as substituents in thearomatic nucleus. The positions of the various groups or atoms attachedto the aromatic nucleus may be any positions relative to one another.

Alkyl phenol sulfides, whose metal salts may be used to prepare thereaction products of the present invention, may be illustrated by thefollowing general classes of compounds:

1. Alkyl phenol thioethers:

OH OH 2. Alkyl phenol disulfides:

OH OH and on on 3. Polymers of alkyl phenol sulfides:

OH OH OH dearth doom tives for lubricating oils, exceptionally goodresults can be obtained by employing metal salts of alkyl phenolsulfides having C1s-C2o branched chain alkyl groups. These can beconveniently radicals particularly preferred in the compounds, it beingunderstood that the list is merely illustrative and does not restrictthe scope of the groups of the formulas. These include n-butyl,

prepared from phenols which have been alkylated 5 isobutyl, tert.-butyl,n-amyl, isoamyl, cyclohexyl, with what are essentially branched chainpolyn-octyl, isooctyl, tert.-octyl, dodecyl, octadecyl, mers of n-buteneobtained as by-product's in the wax chain and C16-C24 branched chainradicals. manufacture of secondary butyl alcohol from pe- Structures ofseveral typical compounds whose troleum refinery C4 hydrocarbonfractions. salts may be reacted with sulfur in accordance It should beunderstood that generally, with the present invention may be given toshow throughout this specification, the term alkyl what is believed tobe the relative positions or the phenol sulfide is meant to include notonly the various groups in the aromatic nuclei, but it is monosulfidesbut also the diand polysulfides to be understood again that theseformulas are and polymers of alkyl phenol sulfides as well. given asillustrations only. These typical exam- Thus, although reaction of analkylated phenol ples are the following: with sulfur dichloride (S012)will give essentially (8) OH OH an alkyl phenol monosulfide, smallamounts of polysulfides and of polymeric materials will also be formed.This is even more usually the result when more than the theoreticallyrequired proportion of sulfur halide is used in preparing the CBHH CaHnalkyl phenol sulfide, as, for example, when 2 (b) OH OH moles of alkylphenol sulfide are treated with 1.5 moles of sulfur dichloride.Similarly, the alkyl phenols may be treated with more than theoreti- 5cal quantities of sulfur monochloride (SzClz) or with mixtures of sulfurmonoand dichloride or can CaHu with first one halide and then the other.(0) OH OH Other compounds Whose metal salts may be used in accordancewith this invention are illus- 3 CZHOC (300ml trated by the following:

HO-(R) CsHa-SeCsHs (R) -OH CsHn s n H (d) OH OH HO(R)CH S C'H(R) OHCsHiOOCUS; 00003111 s H s HO--(R)CsH:SCsH(R)OH 5H" 05H NH Specificexamples of compounds which may be HO (R)CH: S CQH7(R) OH treated withsulfur in accordancewith the present invention include the following,which are CH not to be construed as limiting the invention in HO-(R)C1oH5S-C10H5(R) -OH ny m HO ..(OR) C H s C H (OR) OI-1 Calciumtert.-octyl phenol sulfide Barium 2,4-di-tert.-amyl phenol sulfideHO"'(OR)CGH3SCBHZ(R (OR) OH Cobalt tert.-amyl phenol sulfide I-IO-(R)(NH2)C6H2S-C6H2(NH2) (ID-OH Barium salt of2-hydroxy-3,5-di-tert.-amyl-4- 60 diethylamino diphenyl sulfide fig-(R)(OH) C6H2"'sC6H2(oH) (PU-OH Zinc salt of salicylic acid sulfide octylester HS-(R) CsH3-SC6H3(R)SH Barium 2-stearoyl-4-amyl phenol sulfideMixed calcium-barium tert.-octyl phenol sulfide HO (R) (COR)C6H2SC6H2(R) (COR) OH Tin salt of C1e-C20 branched chain alkyl phenol HO- (R)CeH3-S-C5H4-OROH sulfide Barium salt of bis(2,4-diamyl phenol)-4-amylphenol dithioether (prepared from 2 moles of HO' (R)C6H3-S C6H4OR2,4-di-tert.-amyl phenol and one mole of p- HO-(R)C6H3SC6H4-COORtert.-amyl phenol, sulfurized with sulfur chlo- HO (NH2) ride andneutralized with barium hydroxide) HO (R) When the salts employed arethose of polyvalent metals, it is not essential that all of the valencesHO-(R) C6H3 S C6H3(R)N(R1) (R2) be satisfied by hydroxyaryl sulfidegroups; some o c 1-1 s c 1-1 05 of them may be satisfied by other acidicorganic (straight or branched chain) grgup: sugh as carboxy,daroxy.alkoxy, orgaltlnosu s i ute inorganic aoi groups such as p os- HO(R)C6H3S R' phoric, phosphorous, thiophosphoric, thiophos-HO(R)CsH3-SC5H3(R)NH2 phorous, sulfonic, sulfinic, phosphonic,phosphinic, and the like. In these formulas R represent organ: Thus, forexample, the present invention also i'adlcals'prefera'bly alkyl wincludes reaction products of sulfur with such In all of the abovedescribed type formulas, compounds both general and specific, where R isused to represent an organic radical, such radicals may be Calcium mixedsalt of tert.-amyl phenol sulfide illustrated by the following species,which are 7 and iso-octyl salicylate Aluminum mixed salt of tert.-octylphenol sulfide and stearic acid Tin mixed salt of di-tert.-amyl phenolsulfide and naphthenic acids Barium mixed salt of tert.-octyl phenolsulfide and petroleum mahogany sulfonic acids Nickel mixed salt oftert.-amyl phenol sulfide and amyl xanthic acid Zinc mixed salt ofisododecyl phenol sulfide and methyl cyclohexyl thiophosphoric acidNickel mixed salt of tert.-amyl phenol sulfide and oleic acid Magnesiummixed salt of tert.-octy1 phenol sulfide and cetyl phenol As has beenmentioned previously in this specification, the term phenol sulfide ismeant to include not only the moncsulfide but also disulfides,polysulfides, or polymers or mixtures of any of these in any proportion.

For the objects stated. the metal salts of allzylated phenol sulfideshave been preferably prepared from phenolic compounds readil obtained bysynthetic alkylation of the simple phenols, followed by treatment with asulfur chloride. then neutralization with a metallic base.

Suitable synthetic alkyl phenols for preparing the desired phenolsulfide salts are preferably those containing secondary or tertiaryalkyl radicals because alkylation of a simple phenol occurs more readilywith branched aliphatic reactants. Commonly. the alkylation reactioninvolves. a condensation of olefins with the simple phenols, thereaction being catalyzed by anhydrous metal halides, boron fluoride,hydrofluoric acid, stannic chloride with hydrogen chloride, sulfuricacid. phosphoric acid or certain activated clays. As olefinic reactants,refinery gases containing propylene, 'butylenes, amylenes, etc.. areeconomically useful, although individual olefins or olefin-containingmixtures derived from other sources may be used. Preferred individualolefins are the butenes, amylcnes. and olefin polymers, such ascliisobutylene or triiso-butylene, or normal olefin polymers orcopolymers of normal and secondary or tertiary olefins, or copolymers ofolefins and diolefins. The reaction temperature is usually controlled toavoid side reactions. In employing sulfuric acid, a liquid phasereaction at relatively low temperature is preferred, while withphosphoric acid the reaction may be carried out in the vapor phase.

Suitable alkylated phenols for conversion to phenol sulfides may be thusprepared by alkylating phenol, cresol, naphthol or other phenoliccompounds. High molecular weight alkylated phenols may also be used, forexample, those prepared by condensing phenols with chlorinatedpetrolatum or chlorinated parafiin wax or with a chlorinated kerosene orgas oil. Naturally occurring phenols, such as those obtained by a1-kaline extraction of certain petroleum stocks or those obtained fromcashew nut shell liquid or those obtained from other vegetable oilsources may likewise be used. Halogenated or nitrated phenols will alsofind application in this invention, particularly if the final additiveis to be employed in extreme pressure lubricants.

One class of alkyl phenols whichare particularly preferred are thosewhich have been prepared by alkylation of phenol with an olefin polymersuch as diisobutylene or a refinery butene polymer oil. Alkylation ofphenol with about an equal molar proportion of diisobutylene givesptert.-ctyl phenol, also known as diisobutyl phenol or tetramethyl butylphenol. This phenolic material is especially desirable because of theease of its preparation and because products made from it are highlysatisfactory for the present invention. In many instances, however, ahigher degree of alkylation may be advantageous, and for this reason thephenol may be alkylated with as much as two molecular equivalents ofdiisobutylene to give, under proper conditions, essentiallyditert.-octyl phenol; or it may be alkylated with other olefin polymerssuch as triisobutylene, or other isobutylene polymers. For many purposesit is preferable to employ alkylated phenols having branched chain alkylgroups of from 16 to 30 carbon atoms. Suitable products may be preparedby alkylating phenol with certain of the polymeric materials obtained asby-products in the manufacture of butyl alcohol from petroleum refinerybutenes. These consist essentially of polymers of n-butone with smallpercentages of isobutene and other olefins and give a-lkylated phenolshaving branched chain alkyl groups of l6-20 or 20-24 carbon atoms,depending on the polymeric material used in the alkylation. It should beunderstood that in many cases the alkylation products may be mixtures ofvarious compounds rather than entirely one specific alkyl phenol. andthat it is intended to use such mixtures in practicing this invention.

For conversion of phenols to phenol sulfides the phenol is reacted withsulfur dichloride to produce essentially a phenol mcnosulfide having athioether linkage, while sulfur monochloridc may be used to produceessentially the phenol disulfide. About one-half to one mol of sulfurhalide is used with each mol of phenol. and the reaction is preferablycarried out in a solvent such as dichlorethane, choloform, petroleumnaphtha, benzol, Xylol, toluol. and the like.

For converting the phenol sulfides to metal salts, it is usuallysufficient merely to add a metal or a metallic oxide, hydroxide,sulfide, alkoxide, hydride, or carbide to a mineral oil solution orother solution of the phenol sulfide at an elevated temperature. Thus.barium salts of alkylated phenol sulfides are prepared by reacting thesulfide with barium hydroxide, preferably in the form of the hydrate,Ba(Ol-I)z.8H2O. The calcium salts may be prepared by reacting alkylphenol sulfides with calcium methylate or other calcium alcoholate. Insome instances it may be preferable to prepare heavy metal salts fromthe alkali metal salt by double decomposition. In many cases the metalalkyl phenol sulfide prepared by neutralization with a metal hydroxidemay occur as a hydrated salt. Use of hydrated salts prepared in thismanner or by any other method is also contemplated in the processes ofthe present invention.

In accordance with the present invention, the metallic salt of a phenolsulfide or other metallic derivative of a hydroxy or mercapto aromaticsulfide is caused to react with sulfur. This may be accomplished byadding the sulfur in elemental form to a heated solution of the metalliccompound. The sulfur may be used in any of its a-llotrcpic forms.

In carrying out the reaction described above the proportions of sulfurand metal salt of phenol sulfide are so chosen that from 0.1 to 2.5atomic proportions of sulfur are react-ed with one atomic proportion ofmetal, the preferred ratio being within the limits of about 0.5 to 1.5atomic proportions of sulfur for each atomic prosearch Room portion ofmetal. This preferred ratio gives the products the optimum content ofsulfur to impart to them the maximum amount of inhibiting power.

If desired, the products used in accordance with this invention may beprepared by the simultaneous reaction of a phenol sulfide, a metal oxideor hydroxide and elemental sulfur. However, in order to avoid theformation of oil-insoluble materials, it is preferred to first form themetal salt of the phenol sulfide and then react this with sulfur.

Although the reaction can be brought about by fusing the metal salt withsulfur, it is more convenient to carry out the reaction with the aid ofsolvents, particularly high boiling hydrocarbon solvents, such as xylolor a petroleum fraction. A particularly preferred reaction medium is alubricating oil fraction, since the final reaction product can thus beobtained as a mineral oil concentrate of the desired additive, which maybe conveniently shipped or stored as such and then readily blended withthe lubricating oil base stock in the desired concentration to form afinished lubricating oil blend.

The additives may generally be prepared by first dissolving an alkylatedphenol sulfide in a mineral oil or other suitable solvent and treatingthe same with a metal hydroxide, e. g.,

Ba (OH) 2.8H2O

at about 80-200 C., preferably 110-150 C. After a further period ofheating free sulfur is added, heating being continued at 100-230 C.,preferably at l50-200 C., to complete the reaction. The period ofheating will generally be from about minutes to 1 hour, although in somecases a longer period may be required. When the material will no longerstain a strip of copper immersed in it for about 10 seconds at l80-190C., the reaction is considered complete. The product is then filtered,giving a concentrate of the desired additive. If the products are foundto have a slight odor of hydrogen sulfide, this can be substantiallyeliminated by treating with a small proportion (2-5%) of bariumhydroxide or calcium oxide or hydroxide at 150 C., followed by filteringand blowing with nitrogen at 100- 120 C. In some cases improved productsmay be obtained by heat treatment of the metal phenol sulfide before orafter reaction with sulfur. The heat treatment may be conducted, forexample, at 150 C. for 10l5 hours.

It has been found that good results are obtained when preparing theseadditives in mineral oil if a minor proportion of a higher alcohol, suchas stearyl, lauryl or cetyl alcohol, or wool fat alcohol or the like, isadded to the reaction mixture in which the compounds of the presentinvention are prepared. This alcohol reduces foaming during the processand acts as an auxiliary solvent for the final product. The best resultsare obtained by adding a suflicient quantity of alcohol to give aconcentration of about 3% to about in the final additive concentrate. Ithas been determined by test that substantially none of the higheralcohol enters into the reaction.

It has also been found that products of better oil solubility can oftenbe obtained when carrying out the reaction with sulfur in the presenceof a small proportion of an olefinic material, such as atetraisobutylene, cracked wax or an unsaturated alcohol.

Generally, the additives of the present invention are mostadvantageously blended with lubrieating oil base stocks inconcentrations between the approximate limits of 0.02% and 5.0% andpreferably from 0.1% to 2.0%, although larger amounts may be used forsome purposes. The exact amount of addition agent required for maximumimprovement depends to a certain extent on the particular products used,the nature of the lubricating oil base stock and the general operatingconditions of the engine in which the lubricant is to be employed. Thissame general range of concentration will also be effective when theadditives are to be used in greases and in extreme pressure lubricants,although in the latter instance greater amounts, up to 20%, may also beemployed.

It has been pointed out elsewhere in this specification, it is oftenconvenient to prepare concentrates of the additives in oil, containing,say, to 75% of effective addition agent, the concentrate later beingadded to a suitable lubricating oil base stock to give a finished blendcontaining the desired percentage of additive. Thus, when using aconcentrate, 2.5% of this material may be blended with a suitable basestock to give a finished oil containing 1% of effective addition agent.

In the following examples are described various preparations of productsin accordance with this invention and the results obtained on testingthe same in various lubricating oil blends. It is to be understood thatthese examples, given for illustrative purposes only, are not to beconstrued as limiting the scope of the invention in any way.

Example 1 Tertiary octyl phenol was prepared by alkylating phenol withdiisobutylene, using stannic chloride and HCl catalysts substantially asdescribed in the Buc U. S. Patent 2,332,555.

A 30% solution of tert.-octyl phenol was prepared by dissolving parts byweight of the alkylated phenol in 233 parts of chloroform. Then over aperiod of three hours 37.5 parts of sulfur dichloride was added, thetemperature being maintained at 20--25 C. Agitation was continued for anadditional hour at the same temperature, after which the solution washeated under refiux for two hours. The solvent was stripped off at amaximum temperature of 100 C. and the alkyl phenol sulfide blown withcarbon dioxide until free of H01. The resulting tert.-octyl phenolsulfide was a dark brown resinous product completely soluble in mineraloils.

382 parts by weight of solvent-free tert.-octyl phenol sulfide preparedas above was dissolved in 618 parts of refined mineral lubricating oil(52 seconds Saybolt viscosity at 210 F.) at a temperature of 70-80 C. Tothe agitated oil solution 125 parts of commercial stearyl alcohol wasadded and the temperature was then raised to 110 G. Then 278 parts ofbarium hydroxide octahydrate, Ba(OH)z.8I-I2O, was gradually added insmall portions, the rate of addition being governed by the amount offoaming of the reaction mixture. During this step the mixture was blownwith nitrogen to facilitate removal of water vapor. Following theaddition of the barium hydroxide, agitation and blowing were continuedat C. for 30 minutes, then Hyflo filter aid was added (2 lbs. per 100gallons of mixture), the temperature raised to C. and the mixturefiltered through a filter press, the concentrate being recycled until a,perfectly clear product was obtained. The final product was a mineraloil concentrate containing 40% barium tert.-octyl 11 phenol sulfide, 10%stearyl alcohol, and 50% mineral lubricating oil. It contained 3.2%sulfur and 9.3% barium.

Example 2 As starting material for the preparation of a reaction productof a barium salt, there was used a concentrate containing 40% by weightof barium tert.-octyl phenol sulfide, 10% of stearyl alcohol and 50% ofa refined mineral oil of 52 seconds viscosity Saybolt at 210 F.,prepared as described in Example 1. 500 g. of this concentrate wastreated with 10 g. of sulfur by heating the concentrate to 120 C. andadding the sulfur gradually with agitation over a period of 10 minutes,during which the temperature rose to 190 C. The temperature was thenheld at 160l80 C. for a total reaction period of 2%; hours and the finalproduct filtered. The resulting material contained 4.87% sulfur.

Example 3 The purpose of the following test was to determine thecorrosion inhibiting effect of adding a small quantity of the productprepared as in the preceding example to a lubricating oil base, thisbeing a well refined solvent extracted parafflnic type minerallubricating oil of S. A. E. 20 grade. The oil contained 0.625% ofadditive concentrate prepared in accordance with Example 2, which isequivalent to about 0.25% of the actual additive. A comparative test wasmade with a sample of the unblended oil base.

The tests were conducted as follows: 500 cc. of oil to be tested wasplaced in a glass oxidation tube (13 long and 2 diameter) fitted at thebottom with a ,41" bore air inlet tube perforated to facilitate airdistribution. The oxidation tube was then immersed in a heated bath sothat the oil temperature was maintained at 325 F. during the test. Twoquarter sections of automotive bearings of copper-lead alloy of knownweight having a total area of 25 sq. cm. were attached to opposite sidesof a stainless steel rod which was then immersed in the oil and rotatedat 600 R. P. M., thus providing sufficient agitation of the sampleduring the test. Air was then blown through the oil at the rate of 2 cu.ft. per hour. To increase the severity of the test, the hearings werewashed and weighed at the end of each four hour period and then polishedand reweighed before continuing for another four hour period. Theresults, given in Table I, show the cumulative weight loss at the end ofeach four hour Although in most instances the additives of the presentinvention will of themselves impart sufficient improvement tolubricating oils to give very satisfactory results, still greaterimprovement may often be obtained by employing these addition agents inconjunction with other additives of the detergent type, such as metalsoaps, metal phenates, metal alcoholates, metal phenol sulfides, metalorgano phosphates, thiophos- 12 phates, phosphites and thiophosphites,metal sulfonates, metal thiocarbamates, metal xanthates andthioxanthates, and the like.

Thus the addition agents of our invention may be used in minerallubricating oils in conjunction with one or more of the followingrepresentative materials:

Barium tert.-octyl phenol sulfide Barium di-tert.-amyl phenol'sulfideCobalt tert.-amyl phenol sulfide Tin salt of wax alkylated phenolsulfide Calcium mahogany sulfonates Barium mahogany sulfonates Strontiummahogany sulfonates Magnesium mahogany sulfonates Calcium isohexadecylphenol sulfonate Calcium double salt of octadecyl phenol sulfonic acidBarium phenate-zinc sulfonate of isohexadecyl phenol sulfonic acidCalcium salt of amyl phenol-formaldehyde condensation product Magnesiumcetyl phenate Calcium ortho stearoyl phenate Nickel oleate Calciumdichlorostearate Calcium phenyl stearate Barium octadecylateAluminum-calcium mixed soap of fatty acids from oxidation of petroleumfractions Nickel dibutyl dithiocarbamate Nickel amyl xanthate Bariumdioctyl dithiophosphate Zinc methyl cyclohexyl dithiophosphate Calciumdihexadecyl monothiophosphite Zinc tert.-octy1 phenol sulfidethiophosphate Calcium cetyl phosphate Magnesium lauryl salicylate Zincdiisopropyl salicylate Calcium phenate-barium carboxylate of octadecylsalicylic acid Tin naphthenate Aluminum naphthenate Particularlyadvantageous are lubricant compositions in which the additives of thepresent in vention are employed in conjunction with metal salts ofpetroleum mahogany sulfonic acids. Examples of such compositions includethe following:

Per cent 1. Additive concentrate containing 40% of sulfur-bariumtert.-octyl phenol sulfide reaction product 1.0

Calcium mahogany sulfonates 1.5

Mineral lubricating oil 97.9 2. Additive concentrate containing 35% ofsulfur-calcium tert.-amyl phenol sulfide reaction product 2.5 Bariummahogany sulfonates 1.5 Mineral lubricating oil 96 3. Zinc mahoganysulfonates 2.3

Additive concentrate containing 40% of sulfur-barium-2A-diamyl phenolsulfide reaction product 2.0 Mineral lubricating oil 94 The lubricatingoil base stocks used in the compositions of this invention may bestraight mineral lubricating oils or distillates derived fromparaffinic, naphthenic, asphaltic or mixed base crudes, or, if desired,various blended oils may be employed as well as residuals, particularlythose from which asphaltic constituents have been carefully removed. Theoils may be refined by Dt'irllbil unnuconventional methods using acid,alkali and/or clay or other agents such as aluminum chloride, or theymay be extracted oils produced, for example, by solvent extraction withsolvents of the type of phenol, sulfur dioxide, furfural, dichloro ethylether, nitrobenzene, crotonaldehyde, etc. Hydrogenated oils or whiteoils may be employed as well as synthetic oils prepared, for example, bythe polymerization of oleflns or by the reaction of oxides of carbonwith hydrogen or by the hydrogenation of coal or its products. Incertain instances cracking coil tar fractions and coal tar or shale oildistillates may also be used. Also, for special applications, animal,vegetable or fish oils or their hydrogenated or voltolized products maybe employed, either alone or in admixture with mineral oils.

For the best results the base stock chosen should normally be that oilwhich without the new additives present gives the optimum performance inthe service contemplated. However, since one advantage of the additivesis that their use also makes feasible the employment of lesssatisfactory mineral oils or other oils, no strict rule can be laid downfor the choice of the base stock. Certain essentials must of course beobserved. The oil must possess the viscosity and volatilitycharacteristics known to be required for the service contemplated. Theoil must be a satisfactory solvent for the additive, although in somecases auxiliary solvent agents may be used. The lubricating oils,however they may have been produced, may vary considerably in viscosityand other properties depending upon the particular use for which theyare desired, but they usually range from about 40 to 150 seconds Sayboltviscosity at 210 F. For the lubrication of certain low and medium speedDiesel engines the general practice has often been to use a lubricatingoil base stock prepared from naphthenic or aromatic crudes and having aSaybolt viscosity at 210 F. of 45 to 90 seconds and a viscosity index of0 to 50. vHowever, in certain types of Diesel service, particularly withhigh speed Diesel engines, and in aviation engine and other gasolineengine service, oils of higher viscosity index are often preferred, forexample,*up to '75 to 100, or even higher, viscosity index.

In addition to the materials to be added according to the presentinvention, other agents may also be used, such as dyes, pour depressors,heat thickened fatty oils, sulfurized fatty oils, organo metalliccompounds, metallic or other soaps. sludge dispersers, antioxidants,thickeners; viscosity index improvers, oiliness agents, resins, rubber,olefin polymers, voltolized fats or fatty oils, voltolized mineral oils,and/0r voltolized waxes and colloidal solids such as graphite or zincoxide, etc. Specific examples of such other agents include phenylalpha-naphthylamine, voltolized sperm oil, 2,6-di-tert.-butyl-4-methylphenol, sulfurized sperm oil, p-tert.-amyl phenol sulfide, dibenzyldisulfide, polyisobutylene, sulfurized wax olefins, tricresyl phosphate,diamyl trisulfide, and the condensation product of phenol with a sulfurchloride-diisobutylene reaction product. Solvents and assisting agents,such as esters, ketones, alcohols, amines, nitriles, aldehydes,halogenated or nitrated compounds, and the like, may also be employed.

Assisting agents which are particularly desirable are the higheralcohols having eight or more carbon atoms and preferably 12 to 20carbon atoms. The alcohols may be saturated straight and branched chainaliphatic alcohols such as octyl alcohol (Cal-1110K), lauryl alcohol(C12H25OI-I), cetyl alcohol (CrsHazOI-I), stearyl alcohol, sometimesreferred to as octadecyl alcohOl (CrcHsrOI-I), heptadecyl alcohol(C17H35OH), and the like; the corresponding olefinic alcohols, such asoleyl alcohol; cyclic alcohols, such as naphthenic alcohols; and arylsubstituted alkyl alcohols, for instance, phenyl octyl alcohol, oroctadecyl benzyl alcohol or mixtures of these various alcohols, whichmay be pure or substantially pure synthetic alcohols. One may also usemixed naturally occurring alcohols such as those found in wool fat(which is known to contain a substantial percentage of alcohols havingabout 16 to 18 carbon atoms) and in sperm oil (which contains a highpercentage of cetyl alcohol); and although it is preferable to isolatethe alcohols from those materials, for some purposes, the wool fat,sperm oil or other natural products rich in alcohols may be used per se.Products prepared synthetically by chemical processes may also be usedsuch as alcohols prepared by the oxidation of petroleum hydrocarbons, e.g., paraffin wax, petrolatum, etc.

These assisting agents serve to enhance the detergent and sludgedispersive qualities and aid the solubility of the metal-containingadditives and at the same time impart some oiliness properties to thelubricating oil compositions.

In addition to being employed in crankcase lubricants, the additives ofthe present invention may also be used in extreme pressure lubricants,engine flushing oils, industrial oils, heat transfer media, generalmachinery oils, steam cylinder oils, cutting oils, insulating oils,process oils, rust preventive compositions, hydraulic oils and greases.Also their use in motor fuels, Diesel fuels and kerosene iscontemplated. A particular application in this regard is their use inmotor fuels containing tetraethyl lead or other anti-knock agents, theadditives of the present invention serving not only as antioxidants forthe fuel but also as stabilizers for the anti-knock agent itself. Sinsethese additives exhibit antioxidant properties and are believed also topossess ability to modify surface activity, they may be employed inasphalts, road oils, waxes, fatty oils of animal or vegetable origin,soaps and plastics. Similarly, they may be used in natural and syntheticrubber compounding both as vulcanization assistants and as antioxidants,and generally they may be used in any organic materials subject todeterioration by atmospheric oxygen.

The present invention is not to be considered as limited by any of theexamples described herein which are given by way of illustration only,but it is to be limited solely by the terms of the appended claims.

We claim:

1. As a new composition of matter an oil-soluble sulfur containingproduct obtained by reacting elemental sulfur with a compound of theformula where R is an alkyl radical of at least 5 carbon atoms, X is amember of the group consisting of oxygen and sulfur, M is a divalentmetal of group II of the periodic table and selected from the groupconsisting of calcium, barium, strontium,

magnesium, and zinc, and as is an integer jrom 1 to 4.

2. The method of preparing an oil-soluble sulfur containing producthaving antioxidant properties in the presence of organic materials whichcomprises reacting elemental sulfur with a compound of the formula 16where R is an alkyl radical of at least 5 carbon atoms, X is a member ofthe group consisting of oxygen and sulfur, M is a divalent metal ofgroup II of the periodic table and selected from the group consisting ofcalcium, barium, strontium, magnesium, and zinc, and a: is an integerfrom 1 to 4.

DILWORTH T. ROGERS. JOHN G. McNAB.

